Plate cylinder for rotary printing machines



Feb. 3, 1953 P. DIETRICH PLATE CYLINDER FOR ROTARY PRINTING MACHINES Filed Sept. 19. 19 19 2 SHEETS-SHEET l @N wa\ Q S m aQL H.

INVENTOR BY PAUL DIETRICH Feb. 3, 1953 P. DIETRICH 2,627,229

PLATE CYLINDER FOR ROTARY PRINTING MACHINES Filed Sept. 19, 1949 2 sHEETs--sHI:EI 2

INVENTOR BY PAUL D/ETRICH WI/9M A TTORNE Y8 l the efliciency of the machines.

ties can be avoided immediately.

avoid the requirements of additional operations Patented Feb. 3,1953

PLATE CYLINDER FOR ROTARY PRINTING MACHINES Paul Dietrich, Augsburg, Germany, assignor to Maschinenfabrik Augsburg-Nurnberg A. G., Augsburg, Germany, a corporation of Germany Application September 19, 1949, Serial No. 116,569 In Germany October 1, 1948 9 Claims. 1 This invention relates to certain improvements in regard to the means by which the printing plates are held in place upon the so-called type or printing plate carrying cylinders of rotary printing machines. Said plates so far had been held exclusively at their curved half cylindrical lateral edges since the eccentric-operated clamping jaws developed therefor can be easily arranged at the ends of the cylinder. In this manner it is also possible to chuck two plates side by side between which axially slidable facets anchored in the cylinder hold the plate edges. With one straight edge the plates so far were lying fixedly at stop strips secured in the cylinder and exerting no retaining function whatever against centrifugal forces tending to throw ofi the plates from the cylinder.

The present invention now is based on the knowledge that the printing plates, which in most instances, being in the form of stereotype plates cast from a lead alloy, have a high specific gravity, tend to bulge out at their straight edges owing to the high centrifugal forces produced by the high speeds used nowadays in order to increase This is due to the fact that the stiffness produced by the curvature at the lateral edges is not present at these axially directed edges so that these edges are only laterally supported by the lateral tension device and consequently will be bulged out between these two lateral tension members by the centrifugal forces. These bulges amount to up to 0.35 mm. in case of a size of 47 x 63 cms. of therectangular sheet and 25,000 to 30,000 R. P. M. of the cylinder, and up to. 0.7 mm. in case of a sheet size of 57 x 80 cms. It has been attempted, so far, to compensate this by a particularly soft coat at the printing cylinder and very soft ink rollers.

. However, in this case the pressure is transmitted through the paper, a correct setting of the ink rollers for obtaining a uniform and unexceptional printing is impeded and the considerable noise produced by the continuous clapping of the plates upon the cylinder is hardly reduced thereby. Moreover the plates are prematurely worn off by the rubbing caused thereby.

It is an object of the present invention to provide means for avoiding these drawbacks.

With this object in view, according to the present invention the printing plates which are held at their curved lateral edges are additionally held at their straight edges. Attempts have shown that in this manner the above mentioned difficul- In order to for the attendant, it is suggested, according to a further feature of the invention, to clamp the straight edges of the printing plates simultaneously with the clamping of the lateral edges.

A particularly simple device for carrying out the method according to the invention for holding the printing plates in place on the cylinder comprises a clamping strip, which may be the stop strip and is provided with retaining strips for the straight edge of the printing plate, has inclined surfaces at its ends which, lying against complementary bevelled lips or pressure surfaces are forced towards the form cylinder by the movement of the clamping jaws for the lateral edges of the form plate. A particular advantage of this holding method consists in that the plates them selves can have the conventional shape almost without any change, possibly being provided with a neat deeper-seated abutment or sto surface for lying smoothly against the retaining lipsof the clamping strips.

In order that the common tensioning or clamping of the four edges of the plate may not be impaired by a premature stoppage in one direction or the other of the coordinates, and in order that the tensioning of the curved lateral edges may be ensured by way of positive engagement, the pressure is non-positively transmitted from the clamping jaws to the clamping strips. The clamping strip can be depressed onto the printing cylinder against spring action, so that it, will automatically be lifted ofi from the form cylinder as the clamping jaws are opened. Advantageously the clamping strip is positioned in the middle of the straight edge of the printing plate, since its effect will be felt most at this place. Advantageously it is made so long that practically no noteworthy bulges can be produced and that the specific surface pressure at the edge of the printing plate likewise does not become too high. In order that the clamping strip of this length may be reliably lifted off from the cylinder, it is supported at both ends by a spring. However, the clamping strip is so long and the intermediate press member is so recessed that a part of the straight edge of the form plate is freely exposed for lifting off.

Other and further objects, features and advantages of the invention will be pointed out hereinafter and appear in the appended claims forming part of the application.

In the accompanying drawings a now preferred embodiment of the invention is shown byway .of illustration and not by way oi limitatiomi.

In the drawings:

Fig. 1 is a longitudinal section,

Fig. 2 is a plan view, and

Fig. 3 is a cross sectional view of a type cylinder having the invention applied thereto.

Similar reference numerals denote similar parts in the. different views Referring now to the drawing in greater detail, it will be seen that the type or printing plate carrying cylinder l of a high pressure rotary machine bears at both of its ends in a known manner clamping jaws 2 which are operated, through springs I9, by the clamping ring 4 which is movable by an eccentric 3. Thus, the printing plate 5 is fixedly clamped at its curved, bevelled lateral edges. Positioned between each two printing plates are facet members i which are.

slidable in an axial direction and anchored'in the cylinder at t. The clamping jaws 2 trans.- mit the clamping pressure through springs 8 guided by bolts 9, upon pressure members or intermediate pressure members I I between which clamping strips [3 are pressed on to the cylinder I, through bevelled surfaces I 2, against action of two springs I l. Thus the plates are held, through the retaining lips l5, also at the straight edges 16. When opening the clamping jaws 2 the spring 3 will be relaxed down to its initial tension, the bolt 9 being held by its head 11. The springs i l will lift the clamping strips l3 off from the type cylinder i, so that the plates 5 are released at all sides and can be gripped at their edges exposed by the recesses 28 of the recessed intermediate pressure transmitting members I I, and taken off.

While the one row of clamping strips I3 finds its fixed abutment at the middle ridge member Hi, the spring 8 is located at the corresponding spot of the adjacent row of clamping strips I3, so that the two rows may lie side by side, having very small dimensions which are smaller than the spring diameter. The clamping strip l3 in Fig. 3 acts simultaneously as a stop strip, while the clamping strip l3 holds the straight edge iii of the printing plate 5 againstcentrifugal forces only, with an air gap in a circumferential direction.

While the invention has been described in detail with respect to a now preferred example and embodiment of the invention it will be understood by those skilled in the art after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention and it is intended, therefore, to cover all such, changes and modifications in the appended claims.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1. In a rotary printing machine, in combination, a type cylinder, at least one printing plate and means for holding said printing plate on said type cylinder, said means comprising axially movable first retaining means for holding said plate at its curved lateral. edges and second retaining means engaging the straight edges of said plate, said second retaining means including axially directed clamping strips each having a single lip adapted to overly a recessed straight edge of said printing plate and. bevelled end surfaces, compression springs between said clamping strips and said cylinder, and pressure members having bevelled end surfaces partially overlying said bevelled surfaces of said clamping strips and bevelled complementarily thereto, said first retaining means including means for urg ing said bevelled surfaces on said pressure members slidably against said bevelled surfaces on said strips, for depressing said clamping strips on said cylinder against action of said compression springs.

2. In a rotary printing machine, in'combination, a type cylinder, at least one printing plate and means for holding said printing plate on said type cylinder, said means comprising axially movable first retaining means for holding said plate at its curved" lateral edges and second retaining means engaging the straight edges of said, plate, said second retaining means including axially directed clamping strips each disposed substantially in the middle of a straight edge of the printing plate and having a single lip adapted to overlie the recessed straight edge of said printing plate and bevelled end surfaces, the length of each said strip being substantially less than the length of said straight edge, compression springs between said clamping strips and said cylinder, in the vicinity of the two opposite ends of each clamping strip, and pressure members having bevelled end surfaces partially overlying said bevelled surfaces of said clamping strips and bevelled complementarily thereto, said first retaining means including means for urging said bevelled surfaces on said pressure members slidably against said bevelled surfaces on said strips, for depressing said clamping strips on said cylinder against action of said compression springs.

3. In a rotary printing machine having means for holding the printing plates onto the type cylinder at the curved lateral edges thereof, means for additionally holding said plates by the straight edges thereof comprising at least one clamping strip on said cylinder for the straight edge of a printing plate, said strip having a single retaining lip for gripping the straight edge of one said plate, a pressure member associated with said clamping strip movable axially of said cylinder, and means for urging said strip and said pressure member toward each other, said pressure member having bevelled pressure surfaces adjacent said strip and said strip having pressure surfaces at the ends thereof complementarily bevelled and partially underlying said bevelled surfaces of. said pressure member for urging said strip radially inward toward said cylinder upon movement of said strip toward said pressure member axially of said cylinder to effect the clamping of said one edge of said plate.

4. In a rotary printing machine means for releasably retaining printing plates on a type cylinder by individual pressure contactwith the straight edges thereof comprising a separate. retaining means. engageable withthe straight edge of asingle saidiplate, means for mounting each said retaining means .on said cylinderzfor. radial movement to and from clamping position independently of retaining means for the. edges of other said plateaactuating means for. simultaneously urging all said retaining means into plate retaining position, and means for. positively applying to said actuating means a thrust parallel to the axis of said cylinder, said actuating means including spring means for. transmitting said thrust yieldingly to each said retaining; means providing movement thereof into plate retaining position notwithstanding variations in the. dimensions of said straight edges tobe retained.

5. Apparatus. according. to claim 4 in which at least one. of said retaining means includes a stop abutting one of said straight edges for preventing circumferential movement of said plate around said cylinder.

6. In a rotary printing machine having on the type cylinder thereof retaining means for holding printing plates against said cylinder at the straight axially disposed edges of said plates, means for moving said retaining means radially toward said cylinder into clamping engagement with said straight edges by a force applied in a direction parallel to the axis of said cylinder comprising pressure members on said cylinder associated with said retaining means, beveled pressure surfaces on said members adjacent said retaining means, complementary beveled surfaces on said retaining means partially underlying said surfaces on said members, and means for urging said retaining means and said pressure members toward each other with said surfaces in sliding contact to urge movement of said retaining means radially toward said cylinder into clamping position as said members and said retaining means are moved closer together in a direction parallel to the axis of said cylinder.

7. Apparatus according to claim 6 in which the means for urging said retaining means and said pressure members toward each other in a direction parallel to the cylinder axis includes spring means for applying a resistable force to said retaining means to provide firm clamping engagement at various points along the straight edges of said printing plates notwithstanding dimensional variations of said edges.

8. In a rotary printing machine having a type cylinder and retaining means thereon for holding printing plates against said cylinder at the curved lateral edges thereof, means for additionally holding said plates by the straight axially disposed edges thereof comprising a pair of clamping strips adjacently disposed on said cylinder between the straight edges of a pair of said plates, each of said clamping strips having a single flange projecting over one of said straight edges for clamping said edge, a pair of pressure members associated with each said clamping strip one at each end thereof, and means for urging each said strip and said pressure members associated therewith toward each other, said clamping Number strips having beveled pressure surfaces at the ends thereof adjacent said pressure members, and said pressure members having complementarily beveled pressure surfaces at the ends thereof adjacent said pressure surfaces of said clamping strips and partially overlying the latter for urging said strips radially inward toward said cylinder upon movement of said strips toward said pressure members axially of said cylinder to effect the clamping of each said straight edge by said single flange.

9. In a rotary printing machine, means for releasably retaining printing plates on a type cylinder by individual pressure contact with the straight edges thereof comprising a separate retaining means engageable with the straight edge of a single said plate, means for mounting: each said retaining means on said cylinder for radial movement to and from clamping position independently of retaining means for the edges of other said plates, actuating means for simultaneously urging all said retaining means into plate retaining position, and means for positively applying to said actuating means a thrust parallel to the axis of said cylinder, said actuating means including spring means for transmitting said force yieldably to each said retaining means providing movement thereof radially inwardly into plate retaining position notwithstanding variations in the dimensions of said straight edges to be retained, and additional spring means for urging said retaining means radially outwardly from said cylinder and out of retaining engagement with said plates against the action of said actuating means for positively releasing said straight edges from said retaining means upon relaxation of said axially applied thrust.

PAUL DIETRICH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date 2,075,562 Wood Mar. 30, 1937 

